<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    let i = 0
    let a = 0
    let sum = 0
    do{
        a=2*i+1
        sum=a+sum;
        i=i+1
    }while(i<50)
    console.log(sum)
</script>
</html>